Have a modest Dell Core 2 Duo system w/ 2 hard drives, and use PP3 multicam to edit event performances shot in SD - has worked pretty well, but I've read that extra drives would increase edit performance, so I added 2 more drives (all 7200rpm SATA internal [4 drives is all the motherboard would support]) (boot drive is 250g, the others are 500g, 630g, & 630g.).

To quote Adobe's Premiere Pro CS4 article, "Specify scratch disks to improve system performance", last paragraph: "You can capture audio and video to separate drives, if this is supported by the format codec. (This is not supported by the native DV and HDV capture in Adobe Premiere Pro.)"

So apparently firewire out from my Sony TRV900 can only be captured to a single drive, leaving only the decision of optimal placement of the 4 folders to the 3 drives;